The Bletchley Circle girls may have other things on their mind as they attempt to solve the mysterious double murder at the centre of this new period ITV1 thriller, but costume designer Annie Robbins' most crucial riddle was how to keep the actresses looking authentic amidst the post-war scheming of 1950s London. She tells RadioTimes.com how she brought vintage fashion to life.

Create cracking curves

“From top to toe, I’m quite specific when it comes to period pieces, right down to the underwear! So for filming The Bletchley Circle we sourced actual vintage 1940s and 50s underwear in order to get the right silhouettes and shapes.

Bras and suspenders make the actresses stand and hold themselves in a different way. Until you get that underwear on them, the clothes just don’t look right.”

Scour the aisles

“I wanted to use as many authentic period items as we could, so we hired and bought vintage. I threw a fairly wide net across all the vintage shops and hire houses in London. I love the period, so the difficulty wasn’t a lack of vision as to how I wanted it to look. Finding the pieces was great fun.”

Try it for size

“People are very different shapes and sizes now compared to back then – 1940s and 50s women had much smaller waists, for example. Footwear was another problem for us – finding enough 1940s shoes for size 7 feet was really difficult. I think we’d exhausted the stocks by the end of it.                                                                   They must have just been smaller.”

Give a little TLC

“For The Bletchley Circle, there were costumes that we needed to destroy or distress, but you obviously don’t want to ruin clothing that is 60 years old and has lasted that long! I think it’s a shame when a drama comes along and tears them to pieces, so I prefer to use contemporary reproductions in those instances.”

Make it your own

“With each character, you want to draw out all the subtle, stylistic things that give them their backgrounds. Millie, especially, has got this really exotic, rich past, so she has a definite authoritative take on style. She’s putting things together in a very creative way, and breaking the moulds that existed at that time in the same way that people do now. They were just as inventive with their fashion as women are today – more so because of rationing.”

Get obsessed

“I definitely get completely and utterly immersed in whatever period I’m designing. You’re looking through the archives and photographs, and from that you become fairly obsessed by it. I watched a lot of films that were made in London during the early fifties, and was amazed to see how contemporary and casual people looked. It didn’t seem contrived or ‘period’ in the way we sometimes think it is. You get really caught up in it, and that’s why I love the process.”

The Bletchley Circle starts tonight at 9:00pm on ITV1.